1. Field of the Invention
The present invention relates to an image printer, and more particularly to an image printer having projection exposure means.
2. Description of the Related Art
As an image printer for exposing a film image onto a photosensitive material, there is well-known e.g. an image printer including a projection exposure unit for projecting and exposing a film image onto a photosensitive material and a developing unit for developing the photosensitive material which has been exposed at the projection exposure unit.
The image printer of the above-described type further includes transport means for transporting the photosensitive material via an exposing position of the projection exposure unit to the developing unit. Then, while being transported by this transport means, the photosensitive material undergoes a series of operations from the exposure of the film image to the developing operation, so that the exposure of the film image onto the photosensitive material may be carried out in a convenient manner.
Incidentally, the photosensitive material processed by the above-described image printer is adapted so as to have sensitivity to a wavelength range of the three primary color components, i.e. red, blue and green thereby to cover the entire wavelength range of the visible light. Further, an exposure light source for exposing the photosensitive material having the above-described characteristics too is constructed so as to irradiate white light beam having the wavelength range of the respective three primary color components of red, green and blue.
On the other hand, as an exposure light source, besides the above-described white light source, there is also available a semiconductor light emitting element light source such as a semiconductor laser or a light emitting diode. These semiconductor light emitting element light source is capable of an exposure operation in the unit of pixel, so that this light source may be used also for a so-called digital processing of image information. Further, due to its small light-emitting spot diameter, this type of light source is known to be capable of achieving a higher resolution.
In spite of the above, as the semiconductor light emitting light source, there has been developed one for irradiating red beam or infrared beam. However, there has not yet been developed one capable of obtaining a sufficient light amount in the wavelength range of the blue component. Accordingly, it has been impossible to employ such light source as an exposure light source for the photosensitive materials employed in the conventional image printer of the above-described type.
As far as the exposure of a film image onto a photosensitive material is concerned, the above-described conventional photosensitive material can do in most cases. Still, it has been desired to use also a light source of the above-described type which is not capable of covering the entire wavelength range of the visible light. In this respect, there has been room for improvement.
The present invention attends to the above-described state of the art. A primary object of the present invention is to provide an image printer which allows use of the conventional photosensitive material having sensitivity to the wavelength range of the respective three primary color components and which also allows use, as an exposure light source, a light source incapable of covering the entire wavelength range of the visible light.